How do we find 4and1/4 hours after 11:20pm?

there are 60 minutes in 1 hour, so 1/4 of an hour is 60 (1/4), namely 15 minutes.

11:20pm + 4 hours, is 11+4:20, namely 15:20, of course the time system only uses up to 12, so that has to be 3:20, and then we add the 15 minutes.

11+4: 20 + 15 ... 3:35am.